SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8f74c8728798ae8e2aebd1bddaf181ce958ba26418393611d98eedebf61e394' 
  AND token = 'LTclVvethYKBAT2RzffvACSlfX4Yyp6iN1rKFPfzFr8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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