SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3c78b37ca3b6732b8a28a665e752b84f46fe74ec2442d7a40d20464041affb0' 
  AND token = 'fIfc2gnpf/p68C1iGFdxgLSWjEBOiAePk/egyU/Ayd8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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