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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'c355f32d9c0332cfb0df6a72c6e28818c36f0f5828e65a80754844037a25f206' 
  AND token = '+rBFfod430KwR7YdzREprp6YBoaBZMXEGANvGVkdE2s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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