SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '304d8a1eedbf49795bd63ab0cccccdf8053d23ffc07f75e5c91b8e848f168be9' 
  AND token = 'B+aTFDoVBq4YUtj0byJ14wU1D6ZECoZNZerVv/lFs2s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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