SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '391d2b0621e13027083a2a9bac53782e5c01246c6d1b8d37c5f057698a5ffbb5' 
  AND token = '2TGidsb5CU8tPXWBjs8plLvznW1TENR+Z78lgoQGgqw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}