SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '791c9a3ca704a4fac8a20f6bc427237212f4242ea05e93b745ead2ebaf69a83e' 
  AND token = 'JTJJvCQBOmErVJXQGPWbILc2fQOF+TfWJm3iW8euOLU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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