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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8c6a4baf9ca1c5122369f01b340b9bc121404b0810d0d9137501c4d2cb8b67a' 
  AND token = 'fYZ7NEjnu2TIOykEFxluVGi0cqrsv3kr85evHKPo/Ig=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}