SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '339777dfddde7ba6ab2c6513967060793b99d34f7bcaabcc42af60c8823faaad' 
  AND token = 'LRLrbCU0uYzBrjfFoZCdlw2Ctalxc/mGjEewZJ+sxek=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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