SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f56e25aa3956e007dcee46e067a206987563234c135ba495a3929657be5a2360' 
  AND token = 'LDPPY+HzSwsD+VxcAkgbdO9rFMPeOZabcWkCt8e756Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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