SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e90f577fad1f0655f770ab6e66627a0e48222597e573684aadc0860c604f447' 
  AND token = 'L6wDuZzxjpwdlNc6nYRTaBcHuur695+g/gbjCCJDGKM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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