SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52401c04dfa3fe285dbc566f20b4af34ef5bf503464e3abaa3eb1989ffab8537' 
  AND token = 'x/s/jVDDkxW2lC2VDH3CkgpR7ztOvnMx2LE0qyICGys=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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