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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b12c8315f2fbaafa3265f596d687de1ad18f08bf1490079ddec9b21fa96a74f' 
  AND token = 'TDWJve40CWDpkNXmhPKxN2ePt9TkNb7sgboLynZEYW0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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