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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'c4ac5261c184788e71dedda61d1e3a6fe8b2afbbb3a173a9abe6fd1fef5cf407' 
  AND token = 'sYl+rAEeqoiKkkLxkDdJrP+h+GDvduhGoOhBt2k9eSE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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