SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4fbb08671763e7fd06fa8616f2c0a7166e86d39e0df28a9d3d058a2de9c55fd5' 
  AND token = 'b/0dAJ2xwYVjwfvFe+wZPBLpwb0o1+G+FmPrGFEJt64=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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