SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2d70391e57b2835e83acff94ee41275b47d5940c1ab991042c4cdb1cf12a8d6' 
  AND token = 'I2sOaFnwWEMav0AO4u1eDJt4YNxLCAuhsBMbrjwJlas=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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