SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f0895adb4c6886d36ddb791519e80f12ce6e539fde3867d4667b3fc2387d6045' 
  AND token = 'A9dYB4j412BFpNlOqc/+y9Qx9cSVLK1kbxZFbtM7mhk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}