SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '251592ef8e61f35fd44064a34363e431e89a5e7772cd71d9061701ae67f5721a' 
  AND token = 'T2cO6FdLTsvT87urzhP+3bLw3CPT7i7MalKkUycpDhA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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