SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7499c757ff9145a13ac505d045c230a8619633b00bf38a4d211cf868ee8dfd40' 
  AND token = 'sMMrW+r2u1XPf4dfSIZKsoLSEhIx8l7ynRWrpAey9CE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}