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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad9620410eb7e602f9c137468689c98c20414cf559c9b1a0294975b0ed1711cc' 
  AND token = 'mvb1y3ySp864qnr/4AJMSGZMvsrMO6DQ7Hi4VnIsSxY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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