SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1554dca0b68e1ae36dcff850de0273b6bd0d56abc1fc3f443f310697d58ced6a' 
  AND token = 'SnDSGqqQgVb58JJ1WSUtuwIsbjv1zFphE1CpY3zdRj8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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