SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '82cdfa1794614f3be86f6fd020b1a8c52b230cf89eeb0075d3289a8c1fb68b67' 
  AND token = 'UR4Y+eTKDRukkMMP9FP3rq78hyvODk+wmnNpAheaReM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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