SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cd5d35c4f10d0337eb6dcfa47c9014b373d99233d1b757852a91b6eb532f28e1' 
  AND token = 'C/dMGwvoqsJfWks8dVChRGY+2Ke0OFAQBiRcG/0tnsg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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