SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68cd2fb4f04e3110a7dda7dee9401566b0d191202f885e8b77a4e423acbc2a1f' 
  AND token = 'Fwevt5OhZM+JKMIhwwI9yEDniNLBklDWxDkmUfej1Bk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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