SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '631f2f7ccbcf695098bb527fa02d13572f5b980b82523d880444dcf84a0ee117' 
  AND token = '+L8BP4MRHJ0dBcJvzcVUFAXIRrXfAfk8pEYCPEEB4DA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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