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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f0f277a4d4028d8dde79156c22b780b77245a3308a4e20e7b5c0e1d385de0252' 
  AND token = 'fkVT8MjMrs5zwVyjcJk3T/vdpWJ/W+QB5NYTnSVX/gg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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