SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37383fe84f44410e1aff2df15f72754ee2db9ea73645fefec5e43ea0fb89fa12' 
  AND token = 'z8uhgjPt1A+rYpHFskPRv/6ihZW/ssqC2i93nBwAk64=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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