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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fa1a0f0ab2ba8b15a12ea5725eba703f9fa28f68f3bb8ca248078d0772fad11c' 
  AND token = 'jq3NM/ANsfRhMkhM7Ipt0mwPMqcLNAM4GCKtrT/mywQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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