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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81edc9d4ce43fdf4d9e8a0ca6309b6b5fba3c456ff5e0e7da9279c23ee07a30d' 
  AND token = 'blR4RsXq2z0P0aw56fsNYkYMY4QKT8x1NRz7/WB0H34=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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