SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e721f9d0e2f54035b9bbf00ae08d125440657ad1d242c97f3c6323acd5483b36' 
  AND token = 'udBXUgRUMAIXRKOdGUw5rzzCqr/TuQmsnbwfgvcOh5U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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