SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '568c81cb7ccd17c10c21fdd309fb9795698046e10047c5d15d287cd6cebc0009' 
  AND token = 'yB60uRoMnwEl7RFApNTXjslhy+AXULKw+p3KLlpagnA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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