SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2cd495268550a6281fcb71210a3b34df53e43f5a1851ba49f1cbecdec461cb76' 
  AND token = 'fqmh61gfaF4WmFrnodDmVdSD+Rld4cXWE8nk8VlB538=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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