SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b74eea95ec9075fec449aa16681981b36356f71f348adcaf87d4f78f7354ae51' 
  AND token = 'MrB3R038G3PeKY2iknDyRL3crTweX+ffb0LrgSsvGQ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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