SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '23920336e9e843a24ca0c621eeb02d2a964e8b6a37a2bd215de6697fbad21a33' 
  AND token = 'JCiaAWLZ4GHv5Ml13SOmMPGplzgSZ90Mklzv6u4SgZ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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