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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90b3ae86e91f13e5f6716601f18e545ae9f7c70f0be6ac4ac4799fd61cac1f21' 
  AND token = 'xh3B1rIaYUbTVOrC/+WCV/qHEXBoIks/JL3naR6YJJA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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