SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e403844864b455347fd27d4e859108e86a68c4b652cff811290a807284255632' 
  AND token = 'ZoD7R81RwtRWLPH1Pri0yiwQrwIanCBB5UpfoEF+kNg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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