SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '278d7065b659907ffda1a34721469ad7ff4e85e16471d7aa01d4410071530311' 
  AND token = 'FwkasIP5/V0L6z+veTbjzPfykSzg1IQw4mxS8JWDAAQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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