SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df4b4c56d1ea30981786550b0b235922c2e4717f3b9118712afd662c915c510f' 
  AND token = 'gTfdBQ1ZfWi/BxVoLS5QpRtpd2IHUez0dJRKQmRb7+s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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