SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd2ef197a8540374336d77ce0ba723ff046145e32cd26fadd3c612364af02d33c' 
  AND token = 'JyxdTtyRwlaBkXvNEQd14b+PNbyX+lGrZH3NwCFZGtM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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