SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56789e5e45cfd13ca4263dfb752136011254a8b549c274ecf18495b064203cd5' 
  AND token = '4Vx/U5yTH3jglR3WARFCXXg0+76JXw6UGkZQgOofnGk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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