SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7e8051e62d6d733f8c37c544a0b2897673e49f679f8dcd9b312d7501500ab7c' 
  AND token = 'UQ6d4KFmwyDfV7DY2w4Aix08vBzDITZIjDnuokO+nBU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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