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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c83fe750acc65efc03d2b8b48520e1328d7034210292c876b3e2e5c90dc69b7d' 
  AND token = '+4fpz5Gq/Qour+ChpteZdbpt5mfAORQC1qYuuO5BmLw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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