SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29e4831e430a1ec4d1d627783af2dce306d94116831183d582ad7cdfc9af0e45' 
  AND token = 'o4x/1FvHGDscdF3mHKiWEiIe6YlCfQELT8NkVmscINA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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