SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ca2380ab255b8d695344e99d425d997be456583df8908cec4227850dfb45410e' 
  AND token = 'f6MyHrAzrVyamGasVgOwvfoSTKAisnuAS4B45QNcMqw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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