SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6021a33f9613e1ea8788263a83acae6ecff3e708c4117111ca63092f79259a7' 
  AND token = 'aVWlaQgWlmT74/J/sAW3xZr72NiB7GlLEYf5ZYrxICs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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