SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6995ca4b643ee534b54644c8947502a0d3d66340d38f5fb4849746f27d40134a' 
  AND token = 'vxqL0OKuIUXoB+ZSUcpdqYRAvXtkhv5GSta8bw5Rg5Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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