SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0e23e8972ee625c2422621df2fcae606b45f545b75edd1541bfa00b73980a9d8' 
  AND token = '3CIj/jYsayldCjtNaLXreazsLdDfBi1cbsTRtxft4YE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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