SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7c8f45a34c4fc71471082bbee6682e14edf2421298bf604d6f107664e7db20aa' 
  AND token = 'cKxygNYpNT0YOQ3B/ToCFjZAkvZqrV4FnFz1FRz/IRQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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