SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '846792c2802fabb73c78f03d2c26ce77bdc84305bb9ccfaee3478cb8a9909b56' 
  AND token = 'W+qtluLomi3CY6Cbro4rA+zAMYQzSNm5yVfOoppGGuM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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