SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '26c40486ddd4430227b50e4eb29d30c55bb2459187f802d77c0e5e3620fb2744' 
  AND token = 'QdHHsLhtgsFJ1VjHTDfykSSOfQLWnBXTWlAWTFznEJ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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