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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3fa2e708a7a611466dce3b9ec01d0db635471a015c5ac7a1f89f08a2f7e42790' 
  AND token = '8rn61xaix7AACMG7AT7RIVB0UgBJZhAtHO4MpItyOQM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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