SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77f5fa924bfb8267aff3c2f702c6d81b3516b87238d071e4cf8360107556777b' 
  AND token = 'FPv+KSvjppUwkFsoqQ6aPwT3fDneIoqDbIJQIA9JbW4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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